How large was your nitrate spike and what was the cause of it (if known)? High nitrate levels, even brief or temporary exposures, can be toxic to corals. Any associated detectable ammonia or nitrite? How long has your tank been set up and what other corals are in the tank?
Recommended nitrate levels in a reef tank are <10ppm and ideally at non-detectable levels.
Euphyllia's such as torch corals are fairly hardy in ideal water parameters but can be quite sensitive if the water quality or parameters are less than ideal. When something goes wrong with the water in a reef tank, euphyllia's are among the first to indicate that something is wrong (prolonged tentacle retraction being a sign).
Unfortunately, tentacle detachment (as well as polyp bail-out) is a dire sign particularly with a single-headed torch coral. If the majority of the torch polyp(s) are intact or undamaged it can possibly make a recovery if water and lighting parameters remain ideal, particularly if you have multiple heads (and hopefully unaffected) torch coral.
Last edited by kaybee; 01-05-2012 at 02:41 AM.
African cichlid and saltwater aquariums